CATALOG OF THE MECHANICAL COLLECTIONS 23 



bucket, and the outer end of the bucket makes sharp angles with the 

 sides and bottom. The extreme lip of the bucket is very slightly 

 depressed, suggesting the notched lip developed later. The back of 

 the bucket is provided with lugs, which slip over the rim of the wheel 

 center to which it is attached by bolts passing through the lugs and 

 rim parallel to the shaft. The bucket is made of cast iron, measures 

 about 111/2 inches wide, and weighs 30 pounds. This bucket was made 

 about 1901. (PI. 8, fig. 1.) 



U.S.N.M. no. 310387 is a rectangular bucket similar in most respects 

 to the above. The lip is curved out rather than in, and the back is a 

 flat flange through which the bolts that hold the bucket to the wheel 

 pass in the radial direction. The outside end of the bucket, which 

 is flat, slopes down toward the back so that the back or bottom of the 

 bucket is shorter than the face. This is a large bucket, 17 inches 

 wide, and weighs about 50 pounds. It was made about 1903. (PL 

 8, fig. 2.) 



U.S.N.M. no. 310388 is practically the same as the first (no. 310386), 

 though it is slightly smaller and very much lighter. It has a flange 

 back, is 10^^ inches wide, and weighs about 16 pounds. This bucket 

 was made about 1905. (PI. 8, fig. 3.) 



U.S.N.M. no. 310389 is a very small rectangular bucket similar to 

 the above. It has a flange back, is about 4 inches wide, and weighs 

 2 pounds. This bucket was made about 1911. (PI. 8, fig. 5.) 



U.S.N.M. no. 310390 is a bronze bucket of a recent type. It has 

 the notched lip and ellipsoidal faces of the modern buckets. The 

 bucket bowls are ground but not polished. Cast in the metal is "W. 

 A. Doble— Pat. Sept. 19, 1899." The bucket is 71/2 inches wide, 

 weighs about 9y2 pounds, and has the lug type of back. It was made 

 about 1912. (PI. 8, fig. 4.) 



CONOWINGO HYDROELECTRIC GENERATING STATION, 1928 



Plate 9 



U.S.N.M. no. 310254 ; model ; gift of the Philadelphia Electric Co. ; photograph 

 no. 31017D. 



This model represents a section of the hydroelectric generating sta- 

 tion on the Susquehanna River at Conowingo, Md., a unit of the 

 Philadelphia Electric Co. System. The model is a cross section 

 through the dam and power-house and shows practically every fea- 

 ture of the installation, including the water intakes, butterfly valve, 

 scroll case, water wheel, draft tube and generator of one generating 

 unit, the control room, electrical equipment sections, pipe room, 

 transformers, oil circuit breakers, and the outdoor switching struc- 

 ture on the roof of the power-house. 



